Purification of sulphur dioxide



Sept 2 H924.

F. w. ANDREWS PummcATIoN oF suLPHUR DIOXIDE Fileg Aug. 12,

Patented Sept. 2, i924.

uaiTan sTiaTas FRANK W. ANDREWS, 0F WAPAKONETA, OHIO.

PURIFICATION 0F SULPHUR DIO'XIDE.

Application med Augiist 12,1919. seriai No. 317,016.

To all 'whom t may conce-m:

Be it known that I, FRANK W. ANDREWS, citizen of the United States,,residing at Wapakoneta, in the county of Auglaize and State of Ohio,have invented certain new and useful Improvements in Purification ofSulphur Dioxide, of which the following is a specification.

This invention relates to an apparatus for and method of treatingsulphur dioxide and the like, purifying such chemical agent and chargingthe containers therewith.

The object of the invention is to simplify the charging as well as themeans and mode of operation of purifying' vapoious chemicals such assulphur dioxide and the like, whereby the apparatus will not only becheapened in construction, but'will be more efficient in use, easilymanipulated and controlled, economically charged, and unlikely to et outof repair.

further object of the invention is to provide a new extinguishing agent,and to provide improved means for charging` the containers of thepurified product, and also improved means for purifying the commercialsulphur dioxide and the like prior to its introduction into thecontainers.

With the above primary and other incidental objects in view as will morefully appear in the specification, the invention consists of thefeatures of construction, the parts and combinations thereof, and themode of operation, or their equivalents, as hereinafter described andset forth in the claims.

rlhe drawing herewith is a side elevation, partly' broken away of theapparatus for purifying the sulphur dioxide and the like and forintroducing it into the ultimate containers.

The material employed as an extinguish ing agent is anhydrous liquidsulphur dioxide, highly purified, preferably containing no sulphurtrioxide or other foreign substances. 'lhis liquid is a commercialproduct ordinarily supplied by the manufacturers in liquid form in drumscontaining approximately one hundred and fifty pounds of the product atfifty pounds pressure to the square inch. The liquid has a boiling pointof approximately twelve degrees below zero, niobic color and pungentodor. Be-

heavier than atmosphere and possessed uch expansiye property whendischarged in l5-,ae vicinity of a fire it displaces the oxyv gen uponwhich the continuation of the fire is dependent. The product thuspossesses great merit as a means of extinguishing fire and beinggradually dissipated through the atmosphere it does no incidental damageas is the case when water is used, or when other chemicals in an aqueoussolution are employed.

Referring to the drawings, l is the drum containing the commercialliquid sulphur dioxide. This 'drum and its contents are cooled andmaintained at a low temperature. The drum has been shown in uprightposition in a vat or tank of warming solution 2. The solution 2 may beof any suitable character, the one most used being calcium chloridesolution of approximately twenty six Baume specific gravity. Thisenables the evaporatin of the liquid sulphur dioxide at a comparativelylow temperature. The top of the drum 1 is connected by a pipe or conduit3 with a filter chamber ll. The chamber 4 contains a series of filtermedia through which the gaseous discharge from the drum is passed fromthe bottom of the chamber upward. The pipe 3 being connected to thebottom of the chamber 4, the gas first encounters a stratum 5 ofcharcoal, above which is a stratum of coarse pumice stone. 6, succeededby a layer of fine pumice stone 7, over vwhich lies a layer of felt, S.The successive layers of filter material are pref erably separated bypartitions of close mesh screen cloth. While the filter lmaterials namedare the preferablematerials, it is obvious that other products may besubstituted therefor` without materially affecting the process or finalproduct.

From the top of the filter chamber a pipe or conduit 9 conducts thefiltered gas to the compressor 10. The drum l being thus con nectedthrough the intermediate filter chamber 4 with the intake side of thecompressor 10, the contents of the drum is subjected to a much loweredpressure or partial vacuum. The production of such vacuum or lowering ofpressure within the drum, together with the increased temperature, dueto the submergence of the drum in the warming solution, causes a morerapid evaporationor volatili'zation of the sulphur dioxide. Under thelowered pressure or in the presence of the vacuum, the volatile portionsof the sulphur dioxide will vaporize at a much lower temperature, thanis necessary to vaporize any sulphur trioxide, oil of vitrol or other byfiltration, leaving the vapors of the sulphur dioxide'or the like whichmay be 'carried from the filter chamber 4 to the compressor in a highlyrefined and purified condition. The plpe line 9 is provided with a purgevalve 11 through which air may be admitted to the suction line 9`of thecompressor if sodesired. A vided in the line 9 for in icating the degreeof suction on the filter chamber and through the pipe 9. A globe valve13 is also provided lnthe suction line 9 for the purpose hereaftermentioned.

While the suction pipe 9 might lead directly to, the compressor 1() forconvenience of operation, although not necessary, a vacuum tank '14 isinterposedin the Vpipe linev 9, through Which the gas is drawn in,

its passage from the filter chamber to the compressor. This vacuum tank14 has no function in the treatment of the gas passing therethrough, butis utilized in the preparation of the container to receive its charge.The vacuum tank 14 further serves as an l equalizer to maintain asubstantially uniform degree of vacuum or exhaustion Within the filter.chamber 4, and drum 1, in order that the pressure upon the supplyquantity of commercial sulphur dioxide may not fluctuate with themovement of the compressor piston. The tank 14 is. provided with avacuum gage 15 with the usual control valve which is used as a checkupon the vacuum gage 12, and is further employed to indicate the degreeof vacuum Within the tank when used in exhaustingthe containerspreparatory to charging same. To this end the tank 14 is furtherprovided With a valved branch line. 16 to Which is connected a fiex-iblehose 17.

The compressor 10 is of any suitable type.

That shown in thedrawing is provided with A n discharge pipe 19 leads toa grease trap 22 in which any entrained' oil from the compressor orother heavy foreign materials are precipitated.l A small drain pipe 23conducts the deposited oil from the trap 22 tainers.

ag'e 12 is 'also proback vto the vcompressor crank case, .While the gaspasses from the top of the trap through the pipe line 24 to a condenser25.

This condenser is shown inthe form of a' is supplied through a supplypipe 27 and discharged through a pipe 28. The purified gas admittedtothe condenserv under pressure is liquefied therein, and passes thencethrough a pipe line 29 containing a cut off valve 30 to a receivingvessel 31' in which the refined liquid is stored and from which it isdrawn as needed to fill they con- One of the containers is shown at 32in process of being filled.

Assuming that a fresh tank l has been connected and the apparatus-is tobe set in operation, the purge valve 2O is opened and the compressor isstarted, thereby exhausting the air out of the filter chamber 4, vacuumtank 14 and pipe lines 3 and 9, until the gages 12 and 15 show theproper degree of exhaustion, .and the gas begins-to p'ass over, thecut-o' valve 33 in the discharge line 19 being closed at this time. Theair having been purged from the line, the purge valve 2O is closed andthev cutoff' valve 33- is opened, whereupon the liquefied gas is causedto collect in the receiver 31 after having been passed through thecompressor, the grease trap and condenser as before described. Theapparatus is continued in operation until the vessel 31 is filledor'until sufiicient quantity is vindicated in the gage glass 34communicating therewith. The valve 13 is then closed to retain .anyremaining gas 4in the drum 1 and filter chamber 4, While either thecutoffvalve 33 or 30 or both are closed to retain the liqueed supply ofgas under pressure in the vessel 31. The purge valve 2O is. then'openedand the compressor operated to exhaust the vacuum chamber 14, the intakeof which is closed at 13, and the valve 1G being also closed. Thecontainer 32 to be filled is then temporarily connected with thefiexible hose 17 and the valve 16 is momentarily opened permitting theair contents of the container to be exhausted into the tank 14,producing in the container a partial vacuum. The exhausted container isthen connected with the vessel 31l by mea-ns of the filling connection35 and the valve 36 is opened permitting the liquefied gas to dischargeinto the exhausted container. By first exhausting the container aconsiderable quantity of the liquid gas may be introduced thereinto. Inorder to determine when the proper quantity hasv been discharged intothe container it is placed upon a scale 37 and the charge is determinedby Weight. The container 32 may be of any suitable shape orconstruction. In the dran'- i the a total weight of four poundsisattained.

of liquid, and

Leonesa ing it is shown in the form of a miniature gas drum having atits upper end a discharge nozzle through which the filling isedected,'and a cut ol valve 38. It is tobe understood that the valve38-is closed after the container is exhausted by being connected withthe tank 14, until it is subsequently connected with the supply vessel31. Assuming that the container 1s approximately two and a half inchesin diameter and eleven inches in height, an ample charge would be oneand one-half pounds of the liquified gas, as determined bythe scale.-

rl`he container is first weighed andassuming that it weighs two and ahalf pounds, liquid is admitted from the vessel until There will thenremain an unfilled space of approximately three inches at the to of thecontainerinto which the gas expan s, thus affording pressure for thedischarge of the liquid `when the valve 38 is opene When -in use thecontainer is inverted whereby this pressure chamber or space is abovethe body thedischarge is from the bottom thereof. The character of thematerial is such that lthe constant expansion of the remaining gas inthe container, as the discharge of the contents takes place, maintainsan almost constant pressure.

The sulphur dioxidel (SO2) employed as extinguislung agent has thefurther, desirable characteristic of being a nonconductor ofelectricity. In the case of electrical ignition the use of water' isextremely dangerous, as the' current will sometimes follow the stream orjet with fatal results to the operator. The use of the present agentdoes not involve this danger. The addition of a quantity of' carbondioxide (CO2) to the principalv agent, (SO2) will afford an increasedpressure and obviate possibility of the extinguishing agent freezingabout the nozzle and obstructing the flow. This mixture isv especiallyvaluable for use on airplanes' reaching highA altitudes.

The principal agent S()2 either alone or with the addition of C()2 hasthe further desirable characteristic of producing no smoke, The additionof-two to eight per cent of carbon tetrachloride to the principal agent,i. sulphur dioxide, will produce a heavier gas which will settle moreclosely and uic ly over the' area of fire and more quick y displace theoxygen, but is objectionable in that it produces considerable smoke.From the above .description it will be apparent that there -has thusbeen provided a new use as an 'extinguishing agent for aknown material,and an apparatus and o0 method of handling and treating the material andcharging containers, possessing the particular features of ,advantagebefore enumerated as desirable, butv which obvi- A ously'ls `susceptible-of modification in its 66 form, proportion, detail construction, andarrangement of parts and succession of steps, without departing from theprinciple involved. 1

Having thus described my invention I 10 claim z' 1. The herein describedprocess oftreating sulphur dioxide and the like, consisting insubjecting a liquefied body 'of commercial sulphur dioxide to a artialvacuum and 15 warming the body to induce vaporizationof the morevolatile portion's, leaving .in the container unvolatilized moisture,sulphur trioxide, oil of vitriol and other impurities, drawing thevapors through a filter by which any entrained particles of moisture,oil of vitriol, sulphur trioxide and impurities are removed, subjectingthe resultant vapors to compression,- and condensing the compressed'vapors to liquification. l

2. The herein described method of treating sulphur dioxide consisting insubjecting a body of commercial sulphur dioxide to a low degree of heatin the presence of a vacuum to induce volatilization of the sulphur 0dioxide vapors without vaporizing the moisture content, sulphur trioxideor oil of vitriol which may be contained in the commercial product,liqueyig the resultant vapors and adding thereto a relatively small 91quantity of carbon tetrachloride.

In testimony whereof I have hereunto setl my hand this 26 day of JulyA..D. 1919.

FRANK W. ANDREWS.'

Witnesses:

W. T. CorELAnn, C. B. HAMILTON.`

